Our earlier patent specification EP-A-0128687 describes a bag sealing machine for gathering together the neck of a filled bag and then forming an adhesive tape tie around the gathered together neck. Such machines are widely used, particular in the bakery industry. Typically such machines include a pair of arms which are pivoted at one end and urged together at their opposite ends by compression springs. The open end of a filled bag is urged between the pair of pivoted arms and gathered together by a follow-up member travelling faster than the bag along the pivoted arms. As described in EP-A-0128687 the gathered together neck of the bag is compressed against a first abutment formed by a pair of fixed jaws projecting into the space between the pair of arms, then forced between the jaws onto a piece of adhesive tape and then, together with the piece of adhesive tape forced into contact with a second abutment formed by a second pair of jaws which wraps the adhesive tape around the gathered together neck of the bag and onto itself to complete the tie.
Over the years the speed of operation of such bag sealing machines has increased significantly and one problem that can occur is that the neck of the bag can be torn as it is pushed against the first set of jaws. This is obviously unsatisfactory. The likelihood of the neck being torn depends partly on the speed of throughput of the filled bag, partly on the gauge of the plastic used to form the bags and partly on the weight of the contents of the bag. It also appears that the overall shape of the bag may also influence this because recently attempts have been made to use a gusseted bag for loaves of bread to give a more rectangular appearance to the filled bag and, when operating the bag sealers at high speed with such bags has led to unsatisfactory results.